Traversing mechanisms

ABSTRACT

A traversing mechanism is capable of traversing any one of a number of differently sized leadscrews, which may carry probes, maintaining an accuracy which is substantially constant relative to the size of the traverse. One leadscrew is installed directly in the mechanism, others are contained in cartridges which are installed in the mechanism and are connected to the traversing means of the mechanism. The disclosure also teaches how the mechanism may be adapted to traverse a remotely situated probe, or leadscrews too large to be directly installed therein. A method of using two traversing mechanisms to provide a two dimensional traverse is also described.

Ullltd States Patent 1 1 1111 3,731,547 Fullbrook 1 1 May 8, 1973 541 TRAVERSING MECHANISMS 2,092,563 9 1937 Tucker ..74/424.8 B

I 2,820,945 1/1958 Marsden,Jr... ..73/l94 [751 Fullbmfli 3,374,645 3/1968 Cointe ..66/89 1 dershot, England 3,466,927 9/1969 Magrini ..73/194 Assigneez National Research Development 3,482,459 12/1969 Cantalupo et al. ..74l89.l5 Corporation London England Primary Examiner-Charles J. Myhre [22] Filed: Sept. 21, 1970 Assistant Examiner-Wesle S. Ratliff, Jr.

y 1 pp No 74 103 Attorney-Cushman, Darby & Cushman [57] ABSTRACT [30] Foreign Application Priority Dam A traversing mechanism is capable of traversing any Sept. 22, 1969 Great Britain ..46,470/69 one of a number of differently Sized leadscrews, which DGC.2,1969 Great Britain ..58,802/69 may carry Probes, maintaining an accuracy which is substantially constant relative to the size of the 52 U.S. c1. ..74/s9.15, 74/4241; 8 "averse one leadscrew is installed directly in the 51 1111. C1 ..F16h 27/02 mechanism Others are mined in cartridges which [58] Field of Search 73/194 E 194 are installed in the mechanism and are connected to 15 1 the traversing means of the mechanism. The disclosure also teaches how the mechanism may be adapted to traverse a remotely situated probe, or leadscrews [56] References cued too large to be directly installed therein. A method of UNITED STATES PATENTS using two traversing mechanisms to provide a two dimensional traverse is also described. 2,690,682 10/1954 Passman ..74/44l 3,094,011 6/1963 Bradle 22 Claims, 9 Drawing Figures 13 7b L J 3| ll J /-2| -23l 7a m 9 i 1 NW) Wi -128291 7.. \suF- 'fa -24 Wye/ 2 s, :9! \wawwl/ .61- \e ://A\\\\\ gm 1 27 PATENTED W 75 SHEET 2 1F 6 W Am:

PATENTED MAY 1 75 sum 5 OF 6 A mom 00m mOm um 2. Emil ow 0 IIJIH FL M wow wow A Now 4, 6N 00w E mow wow TRAVERSING MECHANISMS This invention relates to traversing mechanisms of the type which traverse leadscrews.

There are many instances where it is desired to accurately investigate physical properties over an area. For example, in the development of a gas turbine engine it is frequently necessary to investigate the properties of the gas flow in various parts of the engine. Such an in vestigation is carried out by traversing a probe over each area where information is required, the probe conveniently being mounted on the leadscrew of a traversing mechanism. For the investigation to be of value the size of the probe must be small enough, compared with the area being investigated, to cause no significant disturbances in the flow field. Also, the position of the probe head at any time during a traverse must be known to a high degree of accuracy. The latter requirement necessitates that the probe be sufficiently rigid not to distort in the flow.

The compromise which must be made between the size of a probe and its rigidity means that a particular probe will be useful in only a limited number of applications. The versatility of probe traversing mechanisms tends to be limited by the fact that when a mechanism designed for traversing a probe over a large distance is used for a smaller traverse, the accuracy, relative to the total movement, with which the probe position can be determined will be reduced. As a result, traversing mechanisms and probes are frequently made on an individual basis for particular applications. Although the construction of a traversing mechanism is fairly straightforward, the accuracy required calls for precision, and hence accurate machining of components. Traversing mechanisms therefore, tend to be relatively expensive items.

A further restriction on the usefulness of any particular traversing mechanism is imposed by its size, which is large relative to the size of the probe which it traverses. It is therefore frequently difficult or impossible to carry out a traverse in a particular area because of space limitations adjacent to the area.

This specification describes a traversing mechanism capable of traversing any one of a number of differently sized probes over different distances with an accuracy which is substantially constant relative to the size of the traverse. It also describes how the traversing mechanism may be used to traverse a probe which is situated remote from the mechanism.

According to the invention a traversing mechanism comprises a mounting containing linear traverse means and rotational means and is capable of traversing a leadscrew, the linear traverse means being arranged to rotate a linearly restrained nut which is mateable with the leadscrew to linearly traverse the leadscrew, and the rotational means being connectable to the leadscrew and arranged to rotate the leadscrew about its axis or to prevent it from rotating during a linear traverse; the mechanism being also capable, in the absence of the first mentioned leadscrew, of traversing a second leadscrew contained in a shell of a cartridge, the linear traverse means being connectable by a transitional element to a second linearly restrained nut on the second leadscrew, and the rotational means being connectable to the shell which is itself connected to the second leadscrew in such a way that the second leadscrew rotates with the shell.

In a preferred embodiment, the nut of the linear traverse means is linearly restrained by the head of a hollow bolt which is loosely screwed into the mounting unit and keyed to the first mentioned leadscrew. The pitch of the thread on the bolt is the same as that of the first mentioned leadscrew, but oppositely handed, whereby the hollow bolt is forced to rotate when the leadscrew is rotated, but moves in the opposite direction to the leadscrew, forcing the nut of the linear traverse means to move with it, and thus compensating for linear movement of the leadscrew with rotation. When a cartridge is fitted to the unit the above bolt is exchanged for a pair of hollow bolts, an outer bolt screwed to the mounting as before and an inner bolt loosely screwed into the outer one, the pitch of the mating threads on the two bolts being in the opposite sense, but of the same pitch as the new leadscrew. The inner bolt is attached directly or indirectly by splines and/or keys to the leadscrew.

The transitional element may be integral with the linear traverse means or with the second linearly restrained nut, but a preferred form consists of a flange which has on one face, adjacent to the periphery, tongues which fit slots in the nut of the linear traverse means, and which is splined to the nut on the second leadscrew.

Springs are suitably positioned in the mounting unit and in the cartridge to ensure that all play is taken up in one direction.

To enable a probe to be traversed when situated remotely from a traversing mechanism the probe is.

housed at least partly within a casing adapted to be securable to a structure and is arranged to be driveable both linearly and rotationally relative to the casing by means of a flexible drive from the traversing mechanism.

Preferably the flexible drive is a sheathed cable, the sheath being secured at one end to the casing and at the other end to the body of the traversing mechanism whilst the cable driveably connects a leadscrew of the traversing mechanism to the probe.

To assist in eliminating backlash: from the system, the movement of the probe relative to its casing may be biassed in one direction, a preferred form of biassing being by pneumatic pressure.

One embodiment of the invention, and some of the ways in which it may be used, will now be described, by way of example only, with reference to drawings 1 to 9, of which FIGS. 1 to 4 were filed with provisional specification 46470/69, FIGS. 5 and 6 were filed with provisional specification 58802/69 as FIGS. I and 2 respectively, and the accompanying FIGS. 7 to 9 and ofwhich:

FIG. 1 is a crosssectional view of a traversing mechanism adapted to traverse directly a leadscrew, showing the leadscrew in position;

FIG. 2 is a cross-sectional view of a cartridge assembly;

FIG. 3 is a cross-sectional view of the mounting unit of FIG. 1 split into two parts and adapted to accept a cartridge assembly;

FIG. 4 is a similar view to FIG. lot a traversing mechanism with the cartridge assembly of FIG. 3 in position;

FIG. 5 is a sectional view of a probe unit for use in positions remote from a traversing mechanism;

FIG. 6 shows a probe unit, connecting cable and traversing mechanism connected in preparation for carrying out a survey;

FIG. 7 shows diagrammatically an arrangement whereby the traversing mechanism may be used to traverse probes larger than the largest probe which can be directly traversed by the mechanism;

FIG. 8 shows a cross section along VlIIVIIl of FIG. 7, and

FIG. 9 shows diagrammatically an arrangement whereby two traversing mechanisms may be used to give a two-dimensional traverse.

A traversing mechanism (FIG. 1) has a main casing 1 carrying internally linear traversing means comprising a cylindrical shell 4 supported towards one end thereof by a ball bearing 3 and carrying externally a spiral gear wheel 5 which mates with a driveable worm wheel 6 mounted on the casing 1. Within the shell 4 are two internally threaded nuts 7a, 7b keyed to the shell 4 by keys 8. The fit of the nuts 7 with the shell 4 and the keys 8 is such that they may slide axially relative to the shell 4 whilst they must rotate with it. The leading nut, 7a, has in its leading edge (that axially nearest the end of the casing 1) one or more slots 13. Threaded through the nuts 7 is a leadscrew 9 adapted to carry a probe unit (not shown).

Removeably attached to that end of the casing 1 adjacent to the traversing means is an end piece 10 which has a threaded hole into which is loosely screwed a hollow bolt 11. The leadscrew 9 passes through the hole in the bolt 11, but is keyed to the bolt by a key 12 so that it can move axially relative to, but must rotate with, the bolt 11. The bolt 1 1 has the same pitch of thread as the leadscrew 9, but of opposite hand. Between the leading nut 7a and the head of the bolt 11 are thrust washers 14 made of some low friction material such as PTFE.

Also carried within the main casing 1 towards the other end thereof is a rotational means comprising a cylindrical shell 23 supported in the casing 1 by a ball bearing 21 and on the linear traversing mechanism 2, which it overlaps, by a ball bearing 22. The shell 23 is keyed by key 24 to the leadscrew 9 so that the shell 23 and leadscrew 9 must rotate together whilst being free to move axially to one another. A gear wheel 25 is attached externally to the shell 23 and mates with a driveable worm wheel 26.

Between that portion of the shell 23 keyed to the leadscrew 9 by the key 24, and the ball bearing' 22, the

inner diameter of the shell is increased, and a cylindrical collar 27 lies in the space between the shell 23 and the leadscrew 9. The collar 27 is keyed to the leadscrew 9 by a key 28, and abuts against the end face of the keyed portion of the shell 23, the abutment occurring at 45 angled ramps 80 protruding from the adjacent faces.

At the non-abutting face of the collar 27 is a thrust washer 29, similar to the thrust washers 14. A cylindrical spring lies in compression between the washer 29 and the trailing nut 7b of the linear traversing mechanism. A cylindrical spacer 3] prevents the spring 30 from fouling the leadscrew 9. The load of the spring 30 ensures at one end that any play between the driving nuts 7 and the leadscrew 9, and between the end piece 10 and the bolt 11, is taken up in one direction. At the other end of the spring 30 the load on the washer 29 and hence on the collar 27 is converted by the 45 ramps into a tangential load, springing apart the keys 24, 28 and eliminating backlash between these keys and the leadscrew 9.

Before a description is given of the traversing mechanism adapted to accept a probe cartridge, the operation of the above mechanism will be described.

Rotation of the worm wheel 6 causes rotation of the spiral gear 5 and hence of the shell 4 and nuts 7. The nuts 7 are restrained from linear motion by the bolt 11 and the spring 30, and the leadscrew is prevented from rotating by the keys 24, 28 and the rotational mechanism. Consequently the leadscrew 9 is driven linearly without rotation.

Rotation of the worm wheel 26 causes rotation of the spiral gear 25, and hence, as the gear 25 is keyed by keys 24, 28 to the leadscrew 9, rotation of the leadscrew 9. Rotation of the leadscrew 9 in the nuts 7 of the linear motion mechanism causes linear motion of the leadscrew relative to the nuts 7. However, the bolt 11 is keyed to the leadscrew 9 and must rotate with it. As the bolt 11 and leadscrew 9 are oppositely and equally threaded, the motion of the bolt 11 will be equal to, but in the opposite direction to, that of the leadscrew 9 relative to the nuts 7. As has been stated above the keys 12, 24, and 28 allow axial movement of the leadscrew 9 relative to the bolt 11 and rotational traversing mechanism, and the keys 8 allow relative movement of the nuts 7 relative to the shell 4. Consequently the bolt 1 1 will drive the nuts 7 a distance equal and opposite to the distance moved by the leadscrew 9 relative to the nuts 7, and there will be no linear movement of the leadscrew 9 relative to the mounting unit 1.

A probe cartridge, as shown in FIG. 2, has an open ended cylindrical shell 40 which has two main portions, one portion 40a having an outer diameter equal to that of the major diameter of the leadscrew 9 and the other 40b having an outer diameter not greater than that of the minor diameter of the leadscrew 9. The internal diameter of the shell 40 is constant along its length. The larger diameter portion 40a has an external flange 41 near to the end away from portion 40b. The shell 40 has an external keyway 42 and an internal keyway 43. Carried centrally within the shell 40 is a leadscrew 44 having a protruding probe 45. Secured to the leadscrew 44 is a piston 46 which is a sliding fit within the shell 40 and which is keyed by a key 47 to the internal keyway 43 of the shell, the fit of the key 47 being such that the piston 46 may move axially relative to the shell 40.

Screwed onto the leadscrew 44 is a nut 48 having an outer circular section which over most of its length is a sliding fit with the bore of the shell 40 but which has longitudinal splines 49 positioned around its circumference at the end furthest from the shell 40. Separated from the nut 48 by a low friction thrust washer 50 is a hollow tube 51 which has, adjacent the washer 50, an upstanding collar 52 and, over the rest of its length, external splines 53. The tube 51 is internally keyed by a key 54 to a keyway 55 in the leadscrew 44, the fit of the key 54 being such that the tube 51 and leadscrew 44 may move axially relative to each other. Adjacent to that end of the shell 40 furthest from the nut 48 is an internal collar 56 and between this collar and the piston 46 is a spring 57. The end face of the piston 46 may be so shaped that, when the spring 57 is in compression, a

torque is applied to the piston 46, eliminating play in the key 47 and keyway 43.

The mounting unit as prepared for accepting the cartridge is shown in FIG. 3. The leadscrew 9 (FIG. 1) is withdrawn and the end piece 10 removed from the easing 1. A transitional element in the form of a flange 60 having tongues 61 and a central hole with splines 62 is slotted onto the leading nut 7a, the tongues 61 fitting into the slots 13 on the nut 7a.

The bolt 11 is unscrewed from the end piece 10 and replaced by a bolt 11a which is screwed hard down onto a washer 63. The bolt 11a is hollow and is internally threaded at the same pitch as the leadscrew 44 of the cartridge, the directions of the internal threading of the bolt 11a and of the leadscrew 44 being of opposite hand. A hollow bolt 64 is loosely screwed into the bolt 11a. The bolt 64 has internal splines 65 and an inset rim 66 at its head.

The end piece 10 is now replaced on the casing 1, a low friction thrust washer 67 being positioned between the nut 64 and the flange 60.

The probe cartridge is inserted (FIG. 4) from the end of the casing 1 remote from the end piece 10 by aligning the keyway 42 with the keys 24, 28 of the rotational traversing mechanism and pushing it until the splines 53 of the washer 51 mate with splines 65 of the bolt 64 and the collar 52 sits in the rim 66. The thicknesses of the washers 50, 67 are such that the splines 49 of the nut 48 are simultaneously mated with the central splines 62 of the flange 60.

The cartridge is then pushed harder, compressing the spring 57, until the shell slides over the nut 48 and the flange 41 abuts the shell 23 of the rotational means. The flange 41 and shell 23 are then secured together by screws, bolts, clamps or other means. The pressure of the spring 57 takes up play in the leadscrew 55, nut 48, and bolts 64, 11a.

Traversing of the leadscrew 44 is now similar to that of the leadscrew 9. Operation of the worm wheel 6 causes rotation, via the nut 7a and flange 60, of the nut 48, and traverses the leadscrew 44 linearly. Operation of the worm wheel 26 rotates, via the securing means between the flange 41 and the shell 23, the shell 40 and hence, as the shell'40 is keyed to the piston 46 by key 47,the leadscrew 44. Compensation to prevent relative linear movement of the leadscrew 44 in a rotational traverse is provided by the bolt 64, the action of which is identical to that of the bolt 11 as described earlier.

As there can be no requirement for rotational traverses greater than 360, movement of the bolt 64, or the bolt 11, depending on the arrangement of the mechanism, will be minimal, and the length of the bolts 64, 11 can easily be made large enough to ensure that they will not disengage during a rotational traverse.

It can be seen from the above description that adaption of the unit for a probe cartridge involves only four additional items, the flange 60, the bolts 11a and 64, and the low friction washer 67 (which might in practice he one of the washers 14), and some simple adjustments:-- the fitting or substitution of the above items. The design of probe cartridges, flange 60 and washer 67 may be such that the two latter can be used for a wide range of probe cartridges. The bolts lla and 64 must have the same threads per inch, of the opposite thread, as the leadscrew 44, and can therefore best be considered as part of the cartridge.

The accuracy of the unit with a cartridge fitted will be the same as for the main leadscrew for rotational traverses. For linear traverses the accuracy will be a function of the pitch of the threads of the leadscrew.

An arrangement whereby a probe may be traversed when situated remotely from a traversing mechanism will now be described with reference to FIGS. 5 and 6.

FIG. 5 shows a probe unit comprising a hollow cylindrical casing 101 with a circumferential channel 102 in the outer surface adjacent one end 103. One or more holes such as that shown at 104 connect the channel 102 with the bore of the casing 101.

Into the end 103 is screwed a bored nut 105, the bore of which slideably supports a tubular probe 106. An 0- ring 107 is provided in the nut 105 to minimize air loss between the nut 105 and the probe 106. One end 111 of the probe 106 lies outside the casing 101 and the other is supported by a piston 109 which lies slideably within the casing 101. The probe 106 extends to about half way along a bore 108 in the piston 109, the probe and piston being secured together by a grub screw 110a. Fine gauge tubing 112 extends along the center of the probe 106 and through the piston 109, one end 112a of the tubing 112 extending beyond the end 111 of the probe 106 and the other end 112b extending beyond the piston 109.

FIG. 6 shows a probe unit as described above connected to a traversing mechanism and positioned for carrying out a traverse. To assemble the combination the nut 105 is unscrewed from the casing 101 and the probe 106, with piston 109 attached, withdrawn from the casing. A bracket 114 is secured to that end of the casing 101 opposite to the end 103 and a sheath 140 of a sheath and cable combination is secured to the bracket. A cable 141 is passed through the bracket 114 and through the casing 101 and fitted into that part of the bore 108 of the piston 109 not occupied by the probe 106. The cable 141 and piston 109 are secured together by tightening a grub screw l10b. The piston 109 and probe 106 are then re-fitted in the casing 101 and the nut 105 tightened into position.

A collar having a flange 121 is fitted over the end 103 of the casing 101 and locked into position by tightening one or more bolts such as that shown at 122 until they protrude into the channel 102. Av pipe 124in the collar 120 connects with the channel 102. i v

The end 103 of the casing 101 is then inserted into a hole in structure 131 so that the probe protrudes into the area where it is desired to carry out a traverse. The probe unit is locked into position by screws 123 which connect the structure 131 to the flange 121.

The free end of the sheath is now connected to a bracket on a traversing mechanism 151 and the free end of the cable 141 is connected to a leadscrew 152 driveable by the traversing mechanism. The probe 106 will now follow movement, both linear and rotational, ofthe leadscrew 152.

Flexible tubing 115, leading to suitable measuring apparatus (not shown), is connected to the end 1 12b of the tubing 112 and a light spring 116 is attached to the tubing 115 to keep it under tension. Finally, the pipe 124 is connected to an air supply.

In operation, air under pressure is fed through the pipe 124, via the channel 102 and holes 104, to the inside of the casing 101. The air pressure, acting on the piston 109, biasses the piston, and hence the probe 106 and cable 141, towards the bracket 114, and takes up any backlash in the system. The tension due to the spring 116 prevents the tubing 1 15 from getting entangled between the probe 106 and the casing 101.

It will be seen that many alternative constructions of probe unit are possible. For example, as shown, the diameters of the probe 106 and cable 141 are the same and the piston 109 has a bore 108 of constant diameter. This need not be so. The bore 108 may be of stepped diameter to connect a probe and cable of different diameters. Also other forms of biassing, for example, using springs, are possible. The construction of the flanged collar 120 will depend on the location of the probe unit.

In order to allow an alternative assembly procedure, a hole or a slot may be cut adjacent the end of the easing 101 remote from the end 103, so that, with the probe 106 fully retracted, access may be obtained to the grub screw 110)).

One casing 101 may be adaptable for use with a number of probe units 106 of different size, the size of the inner bores of the nut 105 and piston 109 being functions of the probe size. Probes may be so constructed that they may be fitted directly to the leadscrew 152 of the traversing mechanism, or to the leadscrews of cartridges as described with reference to FIG. 2.

The traversing mechanism as described with reference to FIG. 1 may be used for traversing heavy duty probes of a size greater than can be carried by the largest leadscrew which can be fitted to the mechanism. An arrangement by which this may be done is shown in FIGS. 7 and 8.

A frame 200 has two end plates 201, 202. Rigidly mounted between the end plates 201, 202 are a leadscrew 209 and a guide bar 203. A traversing mechanism 1 is mounted on the leadscrew 209, and a slider 204 is slideable on the guide bar 203. A mounting plate 205 is rigidly secured to the traversing mechanism '1 and the slider 204 in such a way that it lies parallel to the end plates 201, 202. A traversable rod 206, adapted to carry a probe (not shown), is mounted on the plate 205 in such a way that it may rotate but not move axially relative to the plate 205. The traversable rod 206 passes through holes in the end frames 201, 202. The holes may incorporate anti-friction bearings and are in any case slack enough to allow free movement of the rod 206 whilst tight enough to ensure that the end plates 201, 202 maintain rigidity of the rod 206.

A gear wheel 207 is secured to the rotatable cylindrical shell 23 (see FIG. 1) of the traversing mechanism 1. It should be noted that in this mode of use, the shell 23 is not keyed to the leadscrew 209. The gear wheel 207 meshes in 1:1 ratio with a gear wheel 208 which is keyed to the traversable rod 206.

In operation, the frame 200 is mounted so that a probe carried by the traversable rod 206 is correctly positioned'in the area to be investigated. Rotation of the worm wheel 6(FIGS. 7 and 1) of the traversing mechanism 1 operates the linear traverse means. As the leadscrew 209 is rigid relative to the frame 200, the traversing mechanism 1 will itself move, traversing with it the mounting frame 205 and hence the traversable rod 206 and probe. Rotation of the worm wheel 26 (FIGS. 7 and 1) rotates the gear wheel 207, hence the gear wheel 208 and traversable rod 206.

A traversing mechanism as described above enables investigations to be made along the line of traverse. In some cases it is required to investigate properties over an area; for example, over a segment of a circle. This may be achieved by carrying out several traverses with the traversing mechanism being re-positioned after each traverse. Such a procedure requires accurate positioning of the traversing mechanism, and can be tedious and time consuming. An arrangement, using two traversing mechanisms as described with reference to FIG. 1, which cuts down the time required and ensures high accuracy, is shown in FIG. 9.

A frame 300 (FIG. 9), similar to the frame 200 shown in FIG. 7, has a rigidly mounted leadscrew 309, a rigidly mounted guide bar 303, a traversing mechanism (not shown in FIG. 9), a slider (not shown in FIG. 9), and a mounting plate 305, arranged in a similar fashion to the items 209, 203, 1, 204 and 205 as described with reference to FIG. 7. A second traversing mechanism 1 is mounted on the mounting plate 305 with its direction of linear traverse at right angles to the direction of traverse of the mounting plate 305 along the leadscrew 309. Thus by using the two traversing mechanisms 1 an accurate two-dimensional survey can be made.

It should be noted that, for clarity, in the drawings and description, certain items, such as the main casing 1 and the traversing units are shown as of unitary construction. It should be understood that, practically, such items may be fabricated from separately machined parts. Similarly, certain constructional details, such as the means for securing the end piece 10 to the main casing 1, have been omitted from the drawings.

Alternative designs of the traversing mechanism and associated items are possible within the scope of the invention. For example a probe cartridge may have a transition piece integral with the nut 48 and adapted to be connected directly with the shell 4 of the longitudinal traverse unit, and a flange 41 adapted to be connected with the inside of the shell 23 of the rotational traverse unit. Such a probe would be inserted from the end of the traversing mechanism 1 adjacent the end piece 10 after removal of the nuts 7. I

The worm wheels 6 and 26 may be operated manually or mechanically to carry out traverses, and position indicators may conveniently be driven from the same wheels. When a mechanical drive is used, the unit may be equipped with limit stops to prevent overshoot of the required traverses.

The unit may be operated by a mechanical drive controlled by a computer programmed to obtain any required sequence of readings.

A traversing mechanism according to the invention, with a selection of comparatively cheap probe units and associated items, and accessories to allow remote siting of the traversing mechanism from the probes, provides an extremely versatile research tool. The versatility can be extended by the addition of frames such as frame 200 as described, and by the use of a second traversing mechanism with a frame such as frame 300 as described above.

What I claim is:

l. A traversing mechanism for lead screw means constituted by a lead screw of a first larger diameter, or constituted by a lead screw of a second smaller diameter, contained in a tubular shell with which the second lead screw is constrained to rotate, the second lead screw and shell thus providing a cartridge that is exchangeable with the first lead screw, the traversing mechanism comprising:

a casing;

first traverse means in said casing for substantially essentially linearly traversing a lead screw means;

second traverse means in said casing for substantially essentially angularly rotating the lead screw means;

a nut, threadable on the lead screw means, said nut being connected with said first traverse means for rotation;

means linearly restraining said nut, so that the lead screw means, rather than the nut, will move axially when the nut is rotated while threaded on the lead screw means;

further in combination with the said second lead screw and shell.

2. A traversing mechanism as claimed in claim 1 wherein the nut on the leadscrew is linearly restrained by a bolt which is loosely screwed into the mounting and which is constrained to rotate with the leadscrew,

the pitch of the thread on the bolt being the same as that of the thread on the leadscrew, but of opposite hand.

3. A traversing mechanism as claimed in claim 2 wherein the transitional element is a flange which has on one face, adjacent to the periphery, tongues which fit slots in the nut of the linear traverse means, and which is splined to the nut on the leadscrew.

4. A traversing mechanism as claimed in claim 2 wherein the leadscrew is connected by a sheathed cable to a remotely situated probe, the probe being housed at least partly within a casing securable to a structure, the sheath being secured at one end to the mounting of the mechanism and at the other end to the casing.

5. A traversing mechanism as claimed in claim 4 wherein the probe movement is biased in one direction by pneumatic pressure acting on a piston secured to the probe and slidable within the casing.

6. A traversing mechanism as claimed in claim 1 further including a spring which acts between the linearly restrained nut and a structure of the rotational means for preventing linear backlash of the lead screw.

7. A traversing mechanism as claimed in claim 6 wherein the nut on the leadscrew is linearly restrained by a bolt which is loosely screwed into the mounting and which is constrained to rotate with the leadscrew, the pitch of the thread on the bolt being the same as that of the thread on the leadscrew, but of opposite hand.

8. A traversing mechanism as claimed in claim 7 wherein the transitional element is a flange which has on one face, adjacent to the periphery, tongues which fit slots in the nut of the linear traverse means, and which is splined to the nut on the leadscrew.

9. A traversing mechanism as claimed in claim 7 wherein the leadscrew is connected by a sheathed cable to a remotely situated probe, the probe being housed at least partly within a casing securable to a structure, the sheath being secured at one end to the mounting of the mechanism and at the other end to the casing.

10. A traversing mechanism as claimed in claim 9 wherein the probe movement is biased in one direction by pneumatic pressure acting as a. piston secured to the probe and slidable within the casing.

11. A traversing mechanism for lead screw means constituted by a lead screw of a first larger diameter, or constituted by a lead screw of a second smaller diameter, contained in a tubular shell with which the second lead screw is constrained to rotate, the second lead screw and shell thus providing a cartridge that is exchangeable with the first lead screw, the traversing mechanism comprising:

a casing;

first traverse means in said casing for substantially essentially linearly traversing a lead screw means;

second traverse means in said casing for substantially essentially angularly rotating the lead screw means;

a nut, threadable on the lead screw means, said nut being connected with first traverse means for rotation;

means linearly restraining said nut, so that the lead screw means, rather than the nut, will move axially when the nut is rotated while threaded on the lead screw means;

a said first lead screw;

the linearly restrained nut being linearly restrained by a bolt which is loosely screwed into the mounting and which is constrained to rotate with the leadscrew, the pitch of the thread on the bolt being the same as that of the thread on the leadscrew, but ofoppositehand 12. A traversing mechanism as claimed in claim 11 wherein the leadscrew is connected by a sheathed cable to a remotely situated probe, the probe being housed at least partly within a casing securalble to a structure, the sheath'being secured at one end to the mounting of the mechanism and at the other end to the casing.

13. A traversing mechanism as: claimed in claim 12 wherein the probe movement is biased in one direction by pneumatic pressure acting on a. piston secured to the probe and slidable within the casing.

14. A traversing mechanism for lead screw means constituted by a lead screw of a first larger diameter, or constituted by a lead screw of a second smaller diameter, contained in a tubular shell with which the second lead screw is constrained to rotate, the second lead screw and shell thus providing a cartridge that is exchangeable with the first lead screw, the traversing mechanism comprising:

a casing;

first traverse means in said casing for substantially es sentially linearly traversing a lead screw means;

second traverse means in said casing for substantially essentially angularly rotating the lead screw means;

a nut, threadable on the lead screw,means, said nut being connected with said first traverse means for rotation;

means linearly restraining said nut, so that the lead screw means, rather than the nut, will move axially when the nut is rotated while threaded on the lead screw means; a said first lead screw;

a spring acting between the linearly restrained nut and a structure of the rotational means for preventing linear back-lash of the lead screw; the linearly restrained nut being linearly restrained by a bolt which is'loosely screwed into the mounting and which is constrained to rotate with the leadscrew, the pitch of the thread on the bolt being the same as that of the thread on the leadscrew, but of opposite hand.

15. A traversing mechanism as claimed in claim 14 wherein the leadscrew is connected by a sheathed cable to a remotely situated probe, the probe being housed at least partly within a casing securable to a structure, the sheath being secured at one end to the mounting of the mechanism and at the other end to the casing.

16. A traversing mechanism as claimed in claim 15 wherein the probe movement is biased in one direction by pneumatic pressure acting on a piston secured to the probe and slidable within the casing.

17. A traversing mechanism for longitudinally extending, retracting and reversably angularly rotating an elongated, helically threaded and longitudinally keyed element such as a probe support, said traversing mechanism including:

a casing;

first generally tubular shell means for surrounding the element throughout a portion of the length of the element;

bearing means journalling the first shell means in the casing for rotation of the first shell means about the longitudinal axis thereof;

first, leading, and second, trailing helically threaded nut means threadably engageable with the helical threading of the element;

first driving means on said casing for reversably rotating said first shell means about the longitudinal axis thereof;

longitudinal key and keyway means interconnecting said first shell means and said first and second helically threaded nut means, so that the threaded nut means must rotate when said first shell means rotates;

so that when said first and second helically threaded nut means are threadably engaged with the element and said first driving 'means is operated to rotate the first shell means about the longitudinal axis thereof, longitudinal axial movement of the element relative to the casing results;

second generally tubular shell means for surrounding the element throughout a portion of the length of the element;

bearing means journalling the second shell means in the casing for rotation of the second shell means about the longitudinal axis thereof;

second driving means on said casing for reversably rotating said second shell means about the longitudinal axis thereof;

longitudinal key and keyway means for longitudinally keying the second shell with respect to the element so that the element may move longitudinally with respect to the shell, but must rotate therewith;

cylindrical collar means for encircling the element throughout a portion of the length of the element;

longitudinal key and keyway means on the cylindrical collar means for longitudinally keying the cylindrical collar means with respect to the element so that the cylindrical collar means may move longitudinally along the element, but must rotate with the element;

angled key means between said cylindrical collar means and said second shell means for providing a ramp-like approach to positive stoppage of rotation between the cylindrical collar means and the second shell means;

a compression coil spring bearing coaxially between the second, trailing helically threaded nut means and the cylindrical collar means for tending to force these two members in axially opposite directions relative to the longitudinal axis of the element, and to, as one effect, tending to force the angled key means toward the recited condition of positive stoppage of rotation between the cylindrical collar means and the second shell means;

an annular end piece for said casing;

radially facing circumferential bearing surface means on said casing and on said end piece for journalling the end piece with respect to the housing, said bearing surface means being structured to permit longitudinal and angular relative movement between the end piece and the casing;

an annular bolt;

internal longitudinal key and keyway means on said annular bolt for longitudinally keying the annular bolt with respect to the element so that the annular bolt may move longitudinally along the element but must rotate with the element;

annular thrust bearing means'axially backing said annular bolt;

complementary helical threading between the annular end piece and the annular bolt, said threading on said bolt being external, of opposite hand and like pitch as the helical threading of said element.

18. The traversing mechanism of claim 17 further including said element, wherein said element is constituted by a lead screw extending out of said casing.

19. The traversing mechanism of claim 18 further including a condition sensing probe, said condition sensing probe being mounted on said lead screw exteriorly of said casing.

20. The traversing mechanism of claim 17 further including said element, wherein said element is constituted by a cartridge, said cartridge comprising:

an externally longitudinally keyed tubular shell having means defining an internal longitudinal keyway;

a helically threaded lead screw received in said tubular shell;

longitudinal key and keyway means provided on said lead screw interconnecting the lead screw and the tubular shell, so that the lead screw may move longitudinally with respect to said tubular shell, but must rotate therewith;

an axially compression coil spring means received in the tubular shell and bearing coaxially between the lead screw and the tubular shell in a sense urging extension of the lead screw with respect to the tubular shell;

surface means on said tubular shell engaging surface means on said second shell means in a sense to prevent relative axial movement between the tubular shell of said cartridge and said second shell means.

21. A traversing mechanism cartridge comprising:

a tubular shell;

longitudinal key and keyway means on the shell for preventing relative rotation between the shell and a portion of said traversing mechanism when said cartridge is mounted therein and the longitudinal key and keyway means is engaged with said portion;

a lead screw coaxially received in the shell and protruding out one end of the shell;

longitudinal key and keyway means between the lead screw and the shell constraining the lead screw to rotate with the shell, but permitting relative axial movement therebetween;

resilient means acting axially between the lead screw and the shell, tending to urge the lead screw outwardly of said one end of the shell;

and axial movement restraining nut means threadably received on the lead screw, said nut means being configured for being so restrained by said traversing mechanism, when said cartridge is mounted therein.

22. Two traversing mechanisms for lead screw means each constituted by a lead screw of a first larger diameter, or constituted by a lead screw of a second smaller diameter, contained in a tubular shell with which the second lead screw is constrained. to rotate, the second lead screw and shell thus providing a cartridge that is exchangeable with the first lead screw, the traversing mechanisms each comprising:

a casing;

first traverse means in said casing for substantially essentially linearly traversing a lead screw means;

second traverse means in said casing for substantially essentially angularly rotating the lead screw means;

a nut, threadable on the lead screw means, said nut being connected with said first traverse means for rotation;

means linearly restraining said nut, so that the lead screw means, rather than the: nut, will move axially when the nut is rotated while threaded on the lead screw means;

means for fixing the disposition of the lead screw means of one of said traversing mechanisms; said fixing means carrying a mounting plate and the other of said traversing mechanisms being mounted on said mounting plate. 

1. A traversing mechanism for lead screw means constituted by a lead screw of a first larger diameter, or constituted by a lead screw of a second smaller diameter, contained in a tubular shell with which the second lead screw is constrained to rotate, the second lead screw and shell thus providing a cartridge that is exchangeable with the first lead screw, the traversing mechanism comprising: a casing; first traverse means in said casing for substantially essentially linearly traversing a lead screw means; second traverse means in said casing for substantially essentially angularly rotating the lead screw means; a nut, threadable on the lead screw means, said nut being connected with said first traverse means for rotation; means linearly restraining said nut, so that the lead screw means, rather than the nut, will move axially when the nut is rotated while threaded on the lead screw means; further in combination with the said second lead screw and shell.
 2. A traversing mechanism as claimed in claim 1 wherein the nut on the leadscrew is linearly restrained by a bolt which is loosely screwed into the mounting and which is constrained to rotate with the leadscrew, the pitch of the thread on the bolt being the same as that of the thread on the leadscrew, but of opposite hand.
 3. A traversing mechanism as claimed in claim 2 wherein the transitional element is a flange which has on one face, adjacent to the periphery, tongues which fit slots in the nut of the linear traverse means, and which is splined to the nut on the leadscrew.
 4. A traversing mechanism as claimed in claim 2 wherein the leadscrew is connected by a sheathed cable to a remotely situated probe, the probe being housed at least partly within a casing securable to a structure, the sheath being secured at one end to the mounting of the mechanism and at the other end to the casing.
 5. A traversing mechanism as claimed in claim 4 wherein the probe movement is biased in one direction by pneumatic pressure acting on a piston secured to the probe and slidable within the casing.
 6. A traversing mechanism as claimed in claim 1 further including a spring which acts between the linearly restrained nut and a structure of the rotational means for preventing linear backlash of the lead screw.
 7. A traversing mechanism as claimed in claim 6 wherein the nut on the leadscrew is linearly restrained by a bolt which is loosely screwed into the mounting and which is constrained to rotate with the leadscrew, the pitch of the thread on the bolt being the same as that of the thread on the leadscrew, but of opposite hand.
 8. A traversing mechanism as claimed in claim 7 wherein the transitional element is a flange which has on one face, adjacent to the periphery, tongues which fit slots in the nut of the linear traverse means, and which is splined to the nut on the leadscrew.
 9. A traversing mechanism as claimed in claim 7 wherein the leadscrew is connected by a sheathed cable to a remotely situated probe, the probe being housed at least partly within a casing securable to a structure, the sheath being secured at one end to the mounting of the mechanism and at the other end to the casing.
 10. A traversing mechanism as claimed in claim 9 wherein the probe movement is biased in one direction by pneumatic pressure acting as a piston secured to the probe and slidable within the casing.
 11. A traversing mechanism for lead screw means constituted by a lead screw of a first larger diameter, or constituted by a lead screw of a second smaller diameter, contained in a tubular shell with which the second lead screw is constrained to rotate, the second lead screw and shell thus providing a cartridge that is exchangeable with the first lead screw, the traversing mechanism comprising: a casing; first traverse means in said casing for substantially essentially linearly traversing a lead screw means; second traverse means in said casing for substantially essentially angularly rotating the lead screw means; a nut, threadable on the lead screw means, said nut being connected with first traverse means for rotation; means linearly restraining said nut, so that the lead screw means, rather than the nut, will move axially when the nut is rotated while threaded on the lead screw means; a said first lead screw; the linearly restrained nut being linearly restrained by a bolt which is loosely screwed into the mounting and which is constrained to rotate with the leadscrew, the pitch of the thread on the bolt being the same as that of the thread on the leadscrew, but of opposite hand.
 12. A traversing mechanism as claimed in claim 11 wherein the leadscrew is connected by a sheathed cable to a remotely situated probe, the probe being housed at least partly within a casing securable to a structure, the sheath being secured at one end to the mounting of the mechanism and at the other end to the casing.
 13. A traversing mechanism as claimed in claim 12 wherein the probe movement is biased in one direction by pneumatic pressure acting on a piston secured to the probe and slidable within the casing.
 14. A traversing mechanism for lead screw means constituted by a lead screw of a first larger diameter, or constituted by a lead screw of a second smaller diameter, contained in a tubular shell with which the second lead screw is constrained to rotate, the second lead screw and shell thus providing a cartridge that is exchangeable with the first lead screw, the traversing mechanism comprising: a casing; first traverse means in said casing for substantially essentially linearly traversing a lead screw means; second traverse means in said casing for substantially essentially angularly rotating the lead screw means; a nut, threadable on the lead screw means, said nut being connected with said first traverse means for rotation; means linearly restraining said nut, so that the lead screw means, rather than the nut, will move axially when the nut is rotated while threaded on the lead screw means; a said first lead screw; a spring acting between the linearly restrained nut and a structure of the rotational means for preventing linear back-lash of the lead screw; the linearly restrained nut being linearly restrained by a bolt which is loosely screwed into the mounting and which is constrained to rotate with the leadscrew, the pitch of the thread on the bolt being the same as that of the thread on the leadscrew, but of opposite hand.
 15. A traversing mechanism as claimed in claim 14 wherein the leadscrew is connected by a sheathed cable to a remotely situated probe, the probe being housed at least partly within a casing securable to a structure, the sheath being secured at one end to the mounting of the mechanism and at the other end to the casing.
 16. A traversing mechanism as claimed in claim 15 wherein the probe movement is biased in one direction by pneumatic pressure acting on a piston secured to the probe and slidable within the casing.
 17. A traversing mechanism for longitudinally extending, retracting and reversably angularly rotating an elongated, helically threaded and longitudinally keyed element such as a probe support, said traversing mechanism including: a casing; first generally tubular shell means for surrounding the element throughout a portion of the length of the element; bearing means journalling the first shell means in the casing for rotation of the first shell means about the longitudinal axis thereof; first, leading, and second, trailing helically threaded nut means threadably engageable with the heLical threading of the element; first driving means on said casing for reversably rotating said first shell means about the longitudinal axis thereof; longitudinal key and keyway means interconnecting said first shell means and said first and second helically threaded nut means, so that the threaded nut means must rotate when said first shell means rotates; so that when said first and second helically threaded nut means are threadably engaged with the element and said first driving means is operated to rotate the first shell means about the longitudinal axis thereof, longitudinal axial movement of the element relative to the casing results; second generally tubular shell means for surrounding the element throughout a portion of the length of the element; bearing means journalling the second shell means in the casing for rotation of the second shell means about the longitudinal axis thereof; second driving means on said casing for reversably rotating said second shell means about the longitudinal axis thereof; longitudinal key and keyway means for longitudinally keying the second shell with respect to the element so that the element may move longitudinally with respect to the shell, but must rotate therewith; cylindrical collar means for encircling the element throughout a portion of the length of the element; longitudinal key and keyway means on the cylindrical collar means for longitudinally keying the cylindrical collar means with respect to the element so that the cylindrical collar means may move longitudinally along the element, but must rotate with the element; angled key means between said cylindrical collar means and said second shell means for providing a ramp-like approach to positive stoppage of rotation between the cylindrical collar means and the second shell means; a compression coil spring bearing coaxially between the second, trailing helically threaded nut means and the cylindrical collar means for tending to force these two members in axially opposite directions relative to the longitudinal axis of the element, and to, as one effect, tending to force the angled key means toward the recited condition of positive stoppage of rotation between the cylindrical collar means and the second shell means; an annular end piece for said casing; radially facing circumferential bearing surface means on said casing and on said end piece for journalling the end piece with respect to the housing, said bearing surface means being structured to permit longitudinal and angular relative movement between the end piece and the casing; an annular bolt; internal longitudinal key and keyway means on said annular bolt for longitudinally keying the annular bolt with respect to the element so that the annular bolt may move longitudinally along the element but must rotate with the element; annular thrust bearing means axially backing said annular bolt; complementary helical threading between the annular end piece and the annular bolt, said threading on said bolt being external, of opposite hand and like pitch as the helical threading of said element.
 18. The traversing mechanism of claim 17 further including said element, wherein said element is constituted by a lead screw extending out of said casing.
 19. The traversing mechanism of claim 18 further including a condition sensing probe, said condition sensing probe being mounted on said lead screw exteriorly of said casing.
 20. The traversing mechanism of claim 17 further including said element, wherein said element is constituted by a cartridge, said cartridge comprising: an externally longitudinally keyed tubular shell having means defining an internal longitudinal keyway; a helically threaded lead screw received in said tubular shell; longitudinal key and keyway means provided on said lead screw interconnecting the lead screw and the tubular shell, so that the lead screw may move longitudinally with respect to said tubular shell, but must rotate therewith; an axially compression coil spring means received in the tubular shell and bearing coaxially between the lead screw and the tubular shell in a sense urging extension of the lead screw with respect to the tubular shell; surface means on said tubular shell engaging surface means on said second shell means in a sense to prevent relative axial movement between the tubular shell of said cartridge and said second shell means.
 21. A traversing mechanism cartridge comprising: a tubular shell; longitudinal key and keyway means on the shell for preventing relative rotation between the shell and a portion of said traversing mechanism when said cartridge is mounted therein and the longitudinal key and keyway means is engaged with said portion; a lead screw coaxially received in the shell and protruding out one end of the shell; longitudinal key and keyway means between the lead screw and the shell constraining the lead screw to rotate with the shell, but permitting relative axial movement therebetween; resilient means acting axially between the lead screw and the shell, tending to urge the lead screw outwardly of said one end of the shell; and axial movement restraining nut means threadably received on the lead screw, said nut means being configured for being so restrained by said traversing mechanism, when said cartridge is mounted therein.
 22. Two traversing mechanisms for lead screw means each constituted by a lead screw of a first larger diameter, or constituted by a lead screw of a second smaller diameter, contained in a tubular shell with which the second lead screw is constrained to rotate, the second lead screw and shell thus providing a cartridge that is exchangeable with the first lead screw, the traversing mechanisms each comprising: a casing; first traverse means in said casing for substantially essentially linearly traversing a lead screw means; second traverse means in said casing for substantially essentially angularly rotating the lead screw means; a nut, threadable on the lead screw means, said nut being connected with said first traverse means for rotation; means linearly restraining said nut, so that the lead screw means, rather than the nut, will move axially when the nut is rotated while threaded on the lead screw means; means for fixing the disposition of the lead screw means of one of said traversing mechanisms; said fixing means carrying a mounting plate and the other of said traversing mechanisms being mounted on said mounting plate. 